1. Departments of Obstetrics and Gynecology of Northwestern University, Chicago, Illinois
2. George Washington University Biostatistics Center, Washington, District of Columbia
3. Departments of Obstetrics and Gynecology, MetroHealth Medical Center-Case Western Reserve University, Cleveland, Ohio
4. The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
5. Departments of Obstetrics and Gynecology, Columbia University, New York, New York
6. Departments of Obstetrics and Gynecology, University of Utah Health Sciences Center, Salt Lake City, Utah
7. Departments of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
8. Departments of Obstetrics and Gynecology, University of Pittsburgh, Pittsburgh, Pennsylvania
9. Departments of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
10. Departments of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama
11. Departments of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
12. Departments of Obstetrics and Gynecology, Wayne State University, Detroit, Michigan
13. Departments of Obstetrics and Gynecology, Brown University, Providence, Rhode Island
14. Departments of Obstetrics and Gynecology, University of Texas Health Science Center at Houston, McGovern Medical School-Children's Memorial Hermann Hospital, Houston, Texas
15. Departments of Obstetrics and Gynecology, Oregon Health and Science University, Portland, Oregon